My standard advice is to use OEM parts in critical locations of the engine because they have a track record of being thoroughly tested and the quality controls on the manufacturing end are more stringent than the aftermarket, however, I decided on this build to see if the aftermarket could deliver since it's more cost-effective and convenient to buy seals, gaskets, etc. as a package.
I built this engine using new parts from the bottom up and the engine has less than 10 hours on it. Specifically, a new OEM cylinder was used and the cylinder head was skimmed .003" at the time the valve seats were recut so the components comprising the joint were 👌. Tightening torques and procedures were, of course, used and referenced from the Honda service manual.
The failure occurred opposite the cam chain side of the cylinder. For those of you new to diagnosing problems you have to look for gas tracking across the gasket. This failure perpetuated slowly and eventually enough coolant pooled in the cylinder while the engine was shut down that at startup it became obvious. A plume of white smoke leaving your tailpipe is a dead giveaway that you’re burning coolant. Prior to that, I was seeing a small amount of coolant blow out of the radiator overflow - another sign of a potential head gasket leak. Hot starting was also harder than normal.
In this case, the manufacturer of the cheap gasket chose to remove the orifices used to control coolant flow from the cylinder into the head. These are the four small holes on the Honda gasket that are much larger on the cheapo. Honda spent energy on strategically applying their coating while cheapo did not. Lastly, there could be differences in materials and formation of the protruding beads that help seal everything up, however, I can't say for sure.
That's up to you to decide. For me, I'll need to be compensated before I run another aftermarket head gasket again. The risk/reward doesn't seem to be worth the minor savings the aftermarket gasket provides.
What do you check if your head gasket fails?
The flatness of the cylinder and cylinder head mating surfaces. Often times gaskets fail because these components overheat and become warped.
Other tips and pointers?
- Clean the engine and surrounding area as best as you can before you open the engine up while it’s in the frame.
- While you have access to your cylinder take a look at the cylinder walls for abnormal wear. Deep striations or scratches are a no-no and cause for concern.
- Check the top of the piston for signs of detonation. Remove any carbon buildup that easily comes off with a paper towel, however, refrain from breaking large deposits free. Carbon deposits are extremely hard and if they get stuck in your ring lands or between the rings and cylinder will cause scratching.
- When installing the new gasket be extremely conscious of the possibility of dirt getting on the gasket mating surfaces. Dirt stuck between the cylinder, gasket, and cylinder head will impeded sealing.
Check out my books - The Two and Four Stroke Dirt Bike Engine Building Handbooks. Each book will walk you through diagnosing engine issues and teach you the right way to rebuild your engine. The books feature stunning, high-quality color pics that make text explanations come to life.
Anybody else get burned and should've known better?